Triple breaststroke world champion Qin Haiyang showed off his versatility by upstaging Olympic gold medallist Wang Shun to qualify fastest for Sunday's men's 200m medley final at the Asian Games.
Qin burst onto the scene at the July world championships in Fukuoka, becoming the first man in history to sweep all three breaststroke titles and also setting a new world record in the 200m.
He carried that scintillating form into day one at the Hangzhou Olympic Aquatic Centre, hitting the wall in 1min 58.72sec.
Qin was pushed hard in his heat by Chinese teammate Wang, who touched a fingertip behind to set up an enticing gold-medal showdown.
Since stunning Britain's Duncan Scott to take Olympic medley gold, Wang has faltered, missing out on the final at the last two world championships.
Japan's 2019 world champion Daiya Seto was third fastest in 1:59.55.
"It wasn't good, but I know I can do better," said a disappointed Seto. "I want to improve my time and look forward to battling the two Chinese swimmers."
Tokyo Olympic gold medallist Zhang Yufei, also from the host nation, fired off a warning shot of her own with a dominant 200m butterfly swim.
The defending champion touched in 2:07.46, more than three seconds clear of teammate Yu Liyan and Japan's up-and-coming Airi Mitsui.
Zhang, fresh from beating a stacked field to win the 100m world title in Fukuoka, turned at the halfway point in her heat two body lengths clear and was cruising.
The 25-year-old, who opted not to race the distance at the world championships, is also set to compete in the 50 and 100 fly, along with the 50 free.
Both China and Japan claimed 19 golds at the Asian Games in 2018, and they are overwhelming favourites to top the medals table once again.
But Japan are in disarray after an awful world championships, finishing 17th with just two bronze and long-time head coach Norimasa Hirai bowing out.
In contrast, China came third behind big guns Australia and the United States after claiming five gold, three silver and eight bronze.
In other races, South Korean sensation Hwang Sun-woo got the better of breakout Chinese freestyler Pan Zhanle in their 100m heat, hitting the wall in 48.54.
But China's Wang Haoyu upstaged them, qualifying fastest in 48.13.
"I got sick a month ago and I had to take a break for four days, so the result is relatively good," said Wang. "For tonight's final I am going to continue to work hard, and swim fast."
In other swimming action, Tang Qianting clocked 29.92 to lower her own Asian 50m breaststroke record, but the Chinese teenager still has work to do to better the 29.16 world best set by Lithuania's Ruta Meilutyte this year.
Two-time world champion Xu Jiayu (53.68) was fastest into the men's 100m backstroke final as he aims to defend his title.